TNM alloys are intermetallic γ-TiAl based alloys for applications in the aerospace and automotive industries due to their properties such as low density, good oxidation resistance and high specific mechanical properties. In order to increase the creep resistance of TNM alloys, the TNM+ alloys have been developed which are alloyed with additional elements such as C and/or Si. The aim of this study was to determine the potential of TNM+ alloys compared to conventional TNM alloys in respect of increasing the operation temperature by enhancing the creep resistance. To this end, creep tests were carried out. Cast and hot isostatically pressed material (cast/HIP) of alloys TNM and TNM+ were compared. Additionally, a closed mathematical description of the creep mechanisms was developed using a face matching function. The intention was to be able to make a wide prediction of the creep behaviour, without performing many time-consuming experiments. Likewise, an alternative way should be established to the known linear analysis methods, such as the Arrhenius plot for the determination of the activation energy and Norton plot for the stress exponent. In addition, the high temperature potential of a fine lamellar microstructure was investigated in the studied alloys, which were adjusted using a specific heat treatment. The idea was to further improve the creep resistance of the coarse lamellar cast/HIP material by decreasing the space between the α2/γ-lamellae. Creep tests were carried out and the results were compared with the cast/HIP material. Scanning electron microscopy combined with X-ray diffraction was applied to assess the microstructural evolution during the creep tests. Complementary Vickers hardness tests were conducted.